/**
 * Copyright (c) 2007, Sun Microsystems, Inc
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above
 *     copyright notice, this list of conditions and the following 
 *     disclaimer in the documentation and/or other materials provided 
 *     with the distribution.
 *   * Neither the name of the TimingFramework project nor the names of its
 *     contributors may be used to endorse or promote products derived 
 *     from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.jdesktop.animation.timing;

import java.util.ArrayList;

/**
 * This class provides a generic wrapper for arbitrary Timers that may be used
 * with the Timing Framework. Animator creates its own internal TimingSource by
 * default, but an Animator can be directed to use a different TimingSource by
 * calling {@link Animator#setTimer(TimingSource)}.
 * 
 * The implementation details of any specific timer may vary widely, but any
 * timer should be able to expose the basic capabilities used in this interface.
 * Animator depends on these capabilities for starting, stopping, and running
 * any TimingSource.
 * 
 * The usage of an external TimingSource object for sending in timing events to
 * an Animator is to implement this interface appropriately, pass in that object
 * to {@link Animator#setTimer(TimingSource)}, which adds the Animator as a
 * listener to the TimingSource object, and then send in any later timing events
 * from the object to the protected method {@link #timingEvent()}, which will
 * send these timing events to all listeners.
 * 
 * @author Chet
 */
public abstract class TimingSource {

	// listeners that will receive timing events
	private ArrayList<TimingEventListener> listeners = new ArrayList<TimingEventListener>();

	/**
	 * Starts the TimingSource
	 */
	public abstract void start();

	/**
	 * Stops the TimingSource
	 */
	public abstract void stop();

	/**
	 * Sets the delay between callback events. This will be called by Animator
	 * if its {@link Animator#setResolution(int) setResolution(int)} method is
	 * called. Note that the actual resolution may vary, according to the
	 * resolution of the timer used by the framework as well as system load and
	 * configuration; this value should be seen more as a minimum resolution
	 * than a guaranteed resolution.
	 * 
	 * @param resolution
	 *            delay, in milliseconds, between each timing event callback.
	 * @throws IllegalArgumentException
	 *             resolution must be >= 0
	 * @see Animator#setResolution(int)
	 */
	public abstract void setResolution(int resolution);

	/**
	 * Sets delay which should be observed by the TimingSource after a call to
	 * {@link #start()}. Some timers may not be able to adhere to specific
	 * resolution requests
	 * 
	 * @param delay
	 *            delay, in milliseconds, to pause before starting timing
	 *            events.
	 * @throws IllegalArgumentException
	 *             resolution must be >= 0
	 * @see Animator#setStartDelay(int)
	 */
	public abstract void setStartDelay(int delay);

	/**
	 * Adds a TimingEventListener to the set of listeners that receive timing
	 * events from this TimingSource.
	 * 
	 * @param listener
	 *            the listener to be added.
	 */
	public final void addEventListener(TimingEventListener listener) {
		synchronized (listeners) {
			if (!listeners.contains(listener)) {
				listeners.add(listener);
			}
		}
	}

	/**
	 * Removes a TimingEventListener from the set of listeners that receive
	 * timing events from this TimingSource.
	 * 
	 * @param listener
	 *            the listener to be removed.
	 */
	public final void removeEventListener(TimingEventListener listener) {
		synchronized (listeners) {
			listeners.remove(listener);
		}
	}

	/**
	 * Subclasses call this method to post timing events to this object's
	 * {@link TimingEventListener} objects.
	 */
	protected final void timingEvent() {
		synchronized (listeners) {
			for (TimingEventListener listener : listeners) {
				listener.timingSourceEvent(this);
			}
		}
	}
}
